Recent research suggests that anxiety disorders may be more common in later life than
previously thought. Among other factors, the presence of comorbid mood disorders and
medical illness confounds accurate assessment and diagnosis of these conditions in the
elderly. There have been few studies, however, examining the structural relationships
between anxiety and depression with older-adult samples, and even fewer have
considered the effect of medical illness on these relationships. This study examined three
established structural models of anxiety and depression, using a clinical sample of older
adults seeking treatment in a primary-care setting (N = 2,163). It was hypothesized that
the presence of comorbid medical illness would act as a moderating variable in
evaluating the fitness of these models. Results indicated that a hierarchical model
represented the most parsimonious fit to the full sample. Tests of factorial invariance
revealed variance in model fit as a function of illness severity and threat, and as a
function of illness chronicity and progressiveness. Specifically, the relationship of
somatic symptoms to anxiety varied by combined severity/threat, as well as by
chronicity/progressiveness. These findings support previous conceptualizations of the
relationship between anxiety and depression. Implications of these results for taxonomy,
assessment, and intervention are discussed.
Palmer, William Michael, 2007, UMSL p. 3